One type of PTCA catheter, called an "over-the-wire" balloon angioplasty catheter, is characterized by having a lumen or passageway throughout its entire length which is adapted for the free movement of a guide wire, which guide wire exits at the catheter's proximal end lying outside of the patient's body.
A second type of PTCA catheter called a "monorail" balloon angioplasty catheter is characterized by having a guide wire passageway that extends within only a comparatively short distal segment of the catheter. The monorail catheter's proximal exit port for the guide wire typically lies approximately 10 inches proximal to the catheter's distal end.
The capabilities of the over-the-wire and monorail types of the catheters are presented in Table 1.
TABLE 1 ______________________________________ OVER- THE- MONO- CAPABILITY WIRE RAIL ______________________________________ 1. Advance balloon catheter over a con- NO YES ventional length guide wire already placed in a coronary artery ("bare wire" technique) 2. Perform catheter exchange without NO YES requiring an extension guide wire or a trapping catheter 3. A single operator can perform a rapid NO YES exchange procedure without requiring a guide wire trapping device 4. Guide wire exchange with balloon YES NO catheter placed across the stenosis (guide wire exchange capability) 5. A single operator can easily perform NO YES the entire balloon angioplasty pro- cedure without an assistant 6. A single operator can rapidly perform NO NO the final 20-25 cm of catheter removal without requiring a guide wire trapping device 7. Easy and precise control of guiding YES NO catheter-balloon catheter interactions at right or left coronary ostium without jeopardizing the position of the guide wire within the coronary artery 8. Advancement of PTCA catheter shaft YES NO through the Tuohy-Borst fitting (attached to guiding catheter) un- encumbered by a guide wire lying outside of the balloon catheter shaft 9. Either over-the-wire or monorail NO NO capabilities are available at any time during an angioplasty procedure while using only one balloon catheter ______________________________________ It should be noted that each design has some significant shortcomings.